the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
A fast sample shuttle to couple high and low magnetic fields. Applications to high-resolution relaxometry
Abstract. Combining high-field high-resolution NMR with an evolution of spin systems at low magnetic field offers many opportunities for the investigation of molecular motions, hyperpolarization and the exploration of field-dependent spin dynamics. Fast and reproducible transfer between high and low fields is required to minimize polarization losses due to longitudinal relaxation. Here, we introduce a new design of a sample shuttle that achieves remarkably high speeds, vmax ~ 27 m.s-1. This hybrid pneumatic/mechanical apparatus is compatible with conventional probes at the high-field center. We show applications to water relaxometry in solutions of paramagnetic ions, high-resolution proton relaxometry of a small molecule and sample shuttling of a solution of a 42 kDa protein. Importantly, this fast sample shuttle system is narrow, with a diameter d = 6 mm for the sample shuttle container based on a standard 5 mm outer diameter glass tube, which should allow near access to the sample for magnetic manipulation at low field.
Competing interests: JAVG and AG are employees, FE is a consultant for, JMT is a former employee and AT an employee of a subcontractor of Bruker Biospin.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.- Preprint
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Status: open (until 21 Feb 2025)
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RC1: 'Comment on mr-2024-25', Anonymous Referee #1, 29 Jan 2025
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This manuscript describes a hybrid pneumatic/mechanical sample shuttle designed to achieve high shuttling speeds between high and low fields. With this approach particularly short travel times are achieved (68 ms for 1020 mm travel). A nice thing about this implementation is that the system is adaptable to conventional NMR probes, expanding its utility without the need for specialized equipment. The authors also demonstrate measurements with small molecules, paramagnetic ions, and protein systems. Comparisons to fast field-cycling relaxometry validate the shuttle's performance, and hence provide a robust basis for the instrument's implementation.
This manuscript presents highly innovative instrumentation that can be implemented at low cost on top of existing NMR instrumentation. Challenges and limitations are adequately discussed. I strongly support publication in its current form.
Citation: https://doi.org/10.5194/mr-2024-25-RC1 -
RC2: 'Comment on mr-2024-25', Anonymous Referee #2, 30 Jan 2025
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General comments
This is an impressive piece of work. A fast sample shuttle has been cleverly designed, skilfully constructed, carefully validated, and convincingly described. I would be happy to see the manuscript published without modification, but invite the authors to consider adding a discussion of the following specific point.
Specific comment
If I have understood it correctly, the highest point to which the sample can be lifted is “almost [the magnet’s] upper closing lid” (line 110) at which point the magnetic field is 36.6 or 46.6 mT for 600 and 700 MHz magnets, respectively. Are lower fields possible? With a suitable modification to the design, could the sample be raised to a point outside the magnet can? If so, would there be space to install a subsidiary magnet that could be used to partially cancel the fringing field of the NMR magnet (as, I believe, has been done in some of the articles mentioned in the Introduction)?
A minor question. Do you have any idea about why the “vibration amplitudes were significantly higher on the FSS system installed on the 600 MHz NMR spectrometer at ENS in Paris” (lines 226-227)?
Technical corrections
Pedantically, the word “rope” suggests something one would use to moor a boat or hang clothes out to dry in the garden. Perhaps “string” or “cord” would more accurately convey an impression of the (presumably) ca. 1 mm diameter length of polyethylene used to lift the sample.
Citation: https://doi.org/10.5194/mr-2024-25-RC2 -
CC1: 'Reply on RC2', Jorge A. Villanueva-Garibay, 12 Feb 2025
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If I have understood it correctly, the highest point to which the sample can be lifted is “almost [the magnet’s] upper closing lid” (line 110) at which point the magnetic field is 36.6 or 46.6 mT for 600 and 700 MHz magnets, respectively. Are lower fields possible? With a suitable modification to the design, could the sample be raised to a point outside the magnet can? If so, would there be space to install a subsidiary magnet that could be used to partially cancel the fringing field of the NMR magnet (as, I believe, has been done in some of the articles mentioned in the Introduction)?
A: The physical constrains imposed by the magnet geometries have set the current limits. However, the minimum field that can be achieved is not limited to that end and it is indeed possible to reach positions outside the NMR magnet vessel. We are currently working on the technology to add to the current system the capability to get much lower fields and it will be addressed in a forthcoming publication.
A minor question. Do you have any idea about why the “vibration amplitudes were significantly higher on the FSS system installed on the 600 MHz NMR spectrometer at ENS in Paris” (lines 226-227)?
A: This is still unfortunately an open question. The ‘twin system’ at Bruker France has never shown such vibrational sideband artifacts (3 times higher at ENS). Bruker has performed several tests at the ENS laboratory that include: optical, acoustic, magnetic, etc., in order to identify possible causes. However, nothing could be concluded from such test results. The main vibrational artifact contribution in the ENS apparatus appears at about 9Hz (very low frequency). It can be (speculation), that this frequency couples with one of the magnet’s fundamental frequencies and keeps resonating for a much longer time at higher amplitude.
Technical corrections Pedantically, the word “rope” suggests something one would use to moor a boat or hang clothes out to dry in the garden. Perhaps “string” or “cord” would more accurately convey an impression of the (presumably) ca. 1 mm diameter length of polyethylene used to lift the sample.
A: We agree with the reviewer and have replaced the word “rope” with the word “cord” throughout the manuscript. For your information, the cord’s diameter is ~ 0.5 mm.
Citation: https://doi.org/10.5194/mr-2024-25-CC1
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CC1: 'Reply on RC2', Jorge A. Villanueva-Garibay, 12 Feb 2025
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